24 



The occasional presence of a columella is a very anomalous feature in this species, not being 

 known to occur in other members uf the genus. Mr. Billings, from an examination of a 

 large number of specimens, concludes, however, that the species must be retained in Zaphren- 

 tis, as he finds a graduated series of forms between those with no columella and those in which 

 this structure is large and well developed. 



Locality and Formation. Extremely abundant in the Corniferous Limestone of Rama's 

 Farm, Port Colborne. Also, in the Hamilton Group of Bosanquet, near Widder. 



14. ZAPHRENTIS SPATIOSA (Billings). 



" Corallum short, turbinate, moderately curved and very broadly expanding. At the 

 margin of the cup about ninety radiating septa, alternately a little unequal, and with their 

 edges broadly rounded, as in Z. prolifica. Length, measured on the side of the greater cur- 

 vature, about three inches ; width of cup two inches and a half. Septal fossette unknown. 



" This species is closely allied to Z. prolifica, and may, perhaps, be united with it when 

 its characters become more fully known" (Billings). 



I have nothing to add to the above brief description, which has evidently been drawn from 

 imperfect specimens. There are only a few examples in my collection, which I should be 

 disposed to refer to this species ; but the reference is uncertain, as hardly anything can be 

 made out of the internal characters of the specimens in question, beyond the fact that they 

 are almost certainly referable to Zaphrcntis, and that the very broadly expanding form sepa- 

 rates them from any other known Corniferous species. 



Locality and Formation. Corniferous Limestone, Rama's Farm, Port Colborne (Billings). 

 Ridgeway and Hagersville (Collection of the author). 



Genus HELIOPHYLLUM (Hall). 



The genus Hdiophyllum is very closely allied toCyathophyllum, and the following are the 

 definitions of it given respectively by Milne Edwards'and Haime, and Mr. Billings: 



1. " Corallum simple. Septal apparatus well developed and producing lateral lamellar 

 prolongations, which extend from the wall towards the centre of the visceral chamber, so as 

 to represent ascending arches, and to constitute irregular central tabulce, and which are united 

 towards the circumference by means of vertical dissepiments." (Milne Edwards and Haime.) 



2. " Corallum simple or aggregate ; radiating septa well developed, obliquely striated on 

 their sides by thin elevated ridges, which extend from the outer wall in an upward curved 

 course towards the centre. These ridges are connected by numerous thin laminse, which 

 divide the spaces between the septa into small sublenticular cells. The transverse diaphragms 

 are thin, flexuous, and confined to the central portion of the coral " (Billings). 



The internal characters which distinguish corals of the genus Hdiophyllum (Hall) are 

 thus of a somewhat complicated description. The septa are well developed, and extend nearly 

 or quite to the centre of the theca, where they are often somewhat twisted ; but there is no 

 columella. A central tabulate area exists, but of very circumscribed dimensions. Externally 

 to this tabulate area, the interseptal loculi are divided into cells or small compartments by the 

 intersection of two sets of dissepiments having different directions. The dissepiments of 

 the first and most conspicuous set are directed from the internal surface of the wall obliquely, 

 inwards and upwards towards the centre, in a succession of arches the convexities of which are 

 turned upwards. These dissepiments doubtless correspond with that circumferential portion 

 of the tabulae which is bent downwards towards the base of the coral in species of Zaphrentis, 

 Clisiophyllum, Diphyphyttum, &c. When these dissepiments are more or less imperfect or have 

 suffered destruction, they leave upon the flat surfaces of the septa a corresponding number of 

 arched striae or ridges. Similarly, in the calice of the coral these dissepiments appear on the 

 free edges of the septa as so many short spines. The dissepiments of the second series are 

 more delicate, more disconnected and much more variable in their direction than those of the 

 preceding series. Sometimes they are nearly vertical, or in other words, are pretty nearly 

 concentric with the theca. Sometimes they are not far from the horizontal, and intersect the 

 dissepiments of the former series at a very acute angle. Most commonly they are directed 

 inwards and downwards from the theca towards the centre, so as to cut the dissepiments of 

 the preceding series nearly at right angles. Decorticated examples of Heliophyllum from the 

 Corniferous Limestone exhibit a most characteristic appearance, duo to the intersection of the 



